The XMLWriter.java Java example source code
/*
* Copyright (c) 2006, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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*/
package com.sun.xml.internal.stream.writers;
import java.io.IOException;
import java.io.Writer;
import com.sun.org.apache.xerces.internal.util.XMLStringBuffer;
/**
* XMLWriter
*
* <code>XMLWriter is not thread safe.
*
* For efficiency this writer buffers the input. Use <code>flush() function
* to explicitly write the data to underlying stream.
*
* This writer is designed in such a way that it atleast buffers the input to the
* <code>size specified. Unless flush is called, it guarantees that
* data in chunks of size equal to or more than <code>size specified will be written.
*
*
* <code>XMLWriter instance can be reused. setWriter() internally clears the
* buffer and stores the reference to newly supplied <code>Writer instance.
*
* @author Neeraj Bajaj Sun Microsystems, inc.
*/
public class XMLWriter extends Writer {
private Writer writer ;
private int size ;
//keep the size of internal buffer more than 'size' required to avoid resizing
private XMLStringBuffer buffer = new XMLStringBuffer(6 * (1 << 11) ); // 6 KB
private static final int THRESHHOLD_LENGTH = 1 << 12 ; // 4 KB
private static final boolean DEBUG = false;
/** Creates the instance of <code>XMLWriter
*/
public XMLWriter(Writer writer){
this(writer, THRESHHOLD_LENGTH);
}
/**
* Creates the instnace of <code>XMLWriter.
*
* atleast buffers the input to the
* <code>size specified.
*/
public XMLWriter(Writer writer, int size){
this.writer = writer ;
this.size = size;
}
/**
* Write a single character. The character to be written is contained in
* the 16 low-order bits of the given integer value; the 16 high-order bits
* are ignored.
*
* <p> Subclasses that intend to support efficient single-character output
* should override this method.
*
* @param c int specifying a character to be written.
* @exception IOException If an I/O error occurs
*/
public void write(int c) throws IOException {
ensureOpen();
buffer.append((char)c);
conditionalWrite();
}
/**
* Write an array of characters.
*
* @param cbuf Array of characters to be written
*
* @exception IOException If an I/O error occurs
*/
public void write(char cbuf[]) throws IOException {
write(cbuf, 0, cbuf.length);
}
/**
* Write a portion of an array of characters.
*
* @param cbuf Array of characters
* @param off Offset from which to start writing characters
* @param len Number of characters to write
*
* @exception IOException If an I/O error occurs
*/
public void write(char cbuf[], int off, int len) throws IOException{
ensureOpen();
//optimization: if data size to be written is more than the 'size' specified,
//do not buffer the data but write the data straight to the underlying stream
if(len > size){
//first write the data that may be present in the buffer
writeBufferedData();
//write directly to stream
writer.write(cbuf, off, len);
}else{
buffer.append(cbuf, off, len);
conditionalWrite();
}
}
/**
* Write a portion of a string.
*
* @param str A String
* @param off Offset from which to start writing characters
* @param len Number of characters to write
*
* @exception IOException If an I/O error occurs
*/
public void write(String str, int off, int len) throws IOException {
write(str.toCharArray(), off, len);
}
/**
* Write a string.
*
* @param str String to be written
*
* @exception IOException If an I/O error occurs
*/
public void write(String str) throws IOException {
//optimization: if data size to be written is more than the 'size' specified,
//do not buffer the data but write the data straight to the underlying stream - nb.
if(str.length() > size){
//first write the data that may be present in the buffer
writeBufferedData();
//write directly to stream
writer.write(str);
}else{
buffer.append(str);
conditionalWrite();
}
}
/**
* Close the stream, flushing it first. Once a stream has been closed,
* further write() or flush() invocations will cause an IOException to be
* thrown. Closing a previously-closed stream, however, has no effect.
*
* @exception IOException If an I/O error occurs
*/
public void close() throws IOException {
if(writer == null) return;
//flush it first
flush();
writer.close();
writer = null ;
}
/**
* Flush the stream. If the stream has saved any characters from the
* various write() methods in a buffer, write them immediately to their
* intended destination. Then, if that destination is another character or
* byte stream, flush it. Thus one flush() invocation will flush all the
* buffers in a chain of Writers and OutputStreams.
*
* @exception IOException If an I/O error occurs
*/
public void flush() throws IOException {
ensureOpen();
//write current data present in the buffer
writeBufferedData();
writer.flush();
}
/** Reset this Writer.
*
* see @setWriter()
*/
public void reset(){
this.writer = null;
buffer.clear();
this.size = THRESHHOLD_LENGTH;
}
/**
* Set the given <code>Writer.
*
* @param Writer Writer.
*/
public void setWriter(Writer writer){
this.writer = writer;
buffer.clear();
this.size = THRESHHOLD_LENGTH;
}
/** Set the given <code>Writer
*
* @param Writer Writer.
* @param int Writer will buffer the character data size, after that data is written to stream.
*/
public void setWriter(Writer writer, int size){
this.writer = writer;
this.size = size;
}
/**
* Returns underlying <code>Writer
*/
protected Writer getWriter() {
return writer;
}
/** write the buffer data, if the buffer size has increased the size specified
*/
private void conditionalWrite() throws IOException {
if(buffer.length > size){
if(DEBUG){
System.out.println("internal buffer length " + buffer.length + " increased size limit : " + size);
System.out.println("Data: ('" + new String(buffer.ch, buffer.offset, buffer.length) + "')");
}
writeBufferedData();
}
}
/** Write the data present in the buffer to the writer.
* buffer is cleared after write operation.
*/
private void writeBufferedData() throws IOException {
writer.write(buffer.ch, buffer.offset, buffer.length);
buffer.clear();
}
/** Check to make sure that the stream has not been closed */
private void ensureOpen() throws IOException {
if (writer == null)throw new IOException("Stream closed");
}
}
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